International Journal of Environmental Research and Public Health Review Disparities in Methods Used to Determine Microplastics in the Aquatic Environment: A Review of Legislation, Sampling Process and Instrumental Analysis Jan Halfar 1,2,* , KateˇrinaBrožová 1, Kristina Cabanovˇ á 1,2, Silvie Heviánková 1, Alena Kašpárková 1 and Eva Olšovská 2,3 1 Faculty of Mining and Geology, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava, Czech Republic; [email protected] (K.B.); [email protected] (K.C.);ˇ [email protected] (S.H.); [email protected] (A.K.) 2 Centre for Advanced and Innovative Technologies, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava, Czech Republic; [email protected] 3 Nanotechnology Centre, CEET, VŠB–Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava, Czech Republic * Correspondence: [email protected] Abstract: Plastic particles smaller than 5 mm, i.e., microplastics, have been detected in a number of environments. The number of studies on microplastics in marine environments, fresh water, wastewater, the atmosphere, and the human body are increasing along with a rise in the amounts of Citation: Halfar, J.; Brožová, K.; plastic materials introduced into the environment every year, all contributing to a range of health Cabanová,ˇ K.; Heviánková, S.; and environmental issues. Although the use of primary microplastics has been gradually reduced Kašpárková, A.; Olšovská, E. Disparities in Methods Used to by recent legislation in many countries, new knowledge and data on these problems are needed to Determine Microplastics in the understand the overall lifecycle of secondary microplastics in particular. The aim of this review is to Aquatic Environment: A Review of provide unified information on the pathways of microplastics into the environment, their degradation, Legislation, Sampling Process and and related legislation, with a special focus on the methods of their sampling, determination, and in- Instrumental Analysis. Int. J. Environ. strumental analysis. To deal with the health and environmental issues associated with the abundance Res. Public Health 2021, 18, 7608. of microplastics in the environment, researchers should focus on agreeing on a uniform methodology https://doi.org/10.3390/ to determine the gravity of the problem through obtaining comparable data, thus leading to new ijerph18147608 and stricter legislation enforcing more sustainable plastic production and recycling, and hopefully contributing to reversing the trend of high amounts of microplastics worldwide. Academic Editors: Chunping Yang and Paul B. Tchounwou Keywords: microplastics; aquatic environment; legislation; determination; water Received: 31 May 2021 Accepted: 14 July 2021 Published: 17 July 2021 1. Introduction Publisher’s Note: MDPI stays neutral Recently, research in microplastics has proliferated due to a number of reasons asso- with regard to jurisdictional claims in ciated with the use of plastics, in general, which have long been part of our daily lives. published maps and institutional affil- Besides the benefits of plastics and microplastics, they have also become pollutants, con- iations. taminating all the constituents of the environment. Plastic waste has lately become one of the most serious environmental issues, as it has low biodegradability and is managed inappropriately [1]. According to the latest data from 2019, the worldwide production of plastics amounted to 370 million tons, of which 58 million tons are reported for Europe Copyright: © 2021 by the authors. alone [2]. Licensee MDPI, Basel, Switzerland. Microplastics are mostly defined as particles smaller than 5 mm [3] and come in differ- This article is an open access article ent shapes such as fibers, pellets, fragments, flakes, and beads [4]. Primary microplastics distributed under the terms and are produced for their abrasive properties, mainly as consumer goods in the cosmetics conditions of the Creative Commons industry or cleaning agents. On the other hand, secondary microplastics are formed by Attribution (CC BY) license (https:// the gradual degradation and subsequent fragmentation of larger plastic particles and are creativecommons.org/licenses/by/ considered the predominant source of microplastic pollution in the environment [5–7]. 4.0/). Int. J. Environ. Res. Public Health 2021, 18, 7608. https://doi.org/10.3390/ijerph18147608 https://www.mdpi.com/journal/ijerph Int. J. Environ. Res. Public Health 2021, 18, 7608 2 of 22 Microplastics have been discovered almost everywhere: in the ocean [8], fresh wa- ter [9], wastewater [10], coastal areas [9,11], soil [12], sediment [13], atmosphere [14], various organisms with different frequencies, feeding patterns and trophic levels [15,16] and in food and agricultural systems [17]. The abundance of these particles may have a potential impact on human health [7]. The methods most commonly used for microplastics’ identification and quantification are infrared spectroscopy with Fourier transform (FTIR) and Raman spectroscopy [18,19]. Other methods used to detect microplastics in various environments include gas chromatog- raphy in conjunction with a mass spectrometry (GC/MS) detector, thermal method (TGA) scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy (SEM EDX), or X-ray fluorescence (XRF) [19–22]. In a number of studies that deal with the analysis of microplastics, we can find different procedures for sample preparation and different methodologies in the analysis of microplas- tics themselves. However, this can cause problems in obtaining valid results [19,23,24]. Related to this are complications in the preparation of comprehensive legislation, which would be based on clear procedures for the preparation, identification and evaluation of microplastics in the environment and would include primary and secondary microplastics. Currently available legislation focuses mainly on microplastics in cosmetics and therefore lacks the constraints necessary to achieve sustainable restrictions on the use of plastic products [12,25,26]. The aim of this review is to: • Provide the reader with information on plastics and microplastics and their occurrence in the environment, specifically in sediments and soil, sea and ocean, fresh water and groundwater (Section2); • Present an overview of currently used methods of the determination of microplastics in water, including the details on sampling and sample processing (Section3); • Review the subsequent instrumental analyses of microplastics in water with a focus on the two most used methodologies, i.e., Raman spectroscopy and infrared spectroscopy with Fourier transformation (Section4); • Provide a critical overview of the legislation on microplastics, namely in the USA, European Union, China, Argentina, UK and Canada (Section5). According to these mentioned sections, this review presents information that demon- strates the complexity of formulating and preparing legislation in the field of microplastics. The information from the studies shows considerable differences not only in the presen- tation of the results, but mainly in the description of the methods used. For this reason, current and forthcoming legislation focuses mainly on restricting disposable plastic mate- rials (such as disposable packaging, microbeads in cosmetics and detergents, and plastic straws), which is important, but little control over its effectiveness is possible. Only if the methodology is uniform, it will be possible to propose laws that cover a much wider range of possible restrictions on microplastic pollution in the environment (such as compul- sory recycling, the production of new plastic products from recycled material, and energy recovery from non-recyclable plastic waste) and their effectiveness can be monitored. 2. Plastics and Microplastics Plastic materials have been used in a wide range of industries due to their versatility and have become indispensable parts of modern life. According to Plastic Europe data, in 2019, 368 million tons of plastics were produced worldwide, out of which 16% are attributed to Europe. Asia holds the lead in the production of plastics with 51% of global production in 2019 [2]. Figure1 shows the plastic demand in Europe in 2019 by each segment, where packaging dominates with 40% of total demand (Figure1). Int.Int. J.J. Environ.Environ. Res.Res. PublicPublic HealthHealth 20212021,18 18, 7608 3 of 22 , , 7608 3 of 22 PLASTIC DEMAND IN EUROPE IN 2019 BY SEGMENT Packaging 17% Building and Construction 3% 40% Automotive 4% Electrical and Electronic 6% Household, Leisure and Sports 10% Agriculture 20% FigureFigure 1.1. PlasticPlastic demanddemand inin EuropeEurope inin 20192019 byby segmentsegment (Data:(Data: PlasticPlastic EuropeEurope 2020).2020). DueDue toto thethe continuouslycontinuously growinggrowing interestinterest inin plastics,plastics, anan identicalidentical growthgrowth trendtrend inin theirtheir productionproduction maymay bebe expectedexpected inin thethe upcomingupcoming years.years. AlmostAlmost halfhalf ofof thethe producedproduced plasticsplastics areare disposable disposable plastic plastic products, products, which which often often turn turn into into waste waste without without further further use. use. It isIt estimatedis estimated that that up up to to 8 million8 million tons tons of of plastics plastics end end up up in in the the oceans oceans each each year year [ 27[27].]. AsAs aa result,result, therethere areare